Safe tire pressure

[Cigar Mike]

Being new to street riding and after 45 years riding dirt. I was wondering how low of tire pressure is safe? I ask because recommended pressures by the manufacturer is not even close to what I run for optimal handling on dirt.

I was talking to a friend that is much more experienced on the street than I am and said that I could run lower pressures. I lowered the pressure to 30 psi in front and rear tires for the ride today and I noticed a big improvement in ride comfort and handling. It was better in strong cross winds as well. Even if the tires wear faster it will be worth it for the improvement.

 

[showkey]

Good question......how low is too low ? .............

I think many manufactures now error on relative high inflation recommendations and only publish "one pressure that fits all riders and conditions"..........this avoids the issues with heavy bikes, fully loaded, at high speed that combined causes quick excessive wear that can end up in tire failure while underway.

For certain lower pressure, load and high speed develope more heat in the tire........which is a bad thing. A good test would be........use a infrared temp gun and run different pressures at the same speed and measure the temp changes and compare the results recommended tire pressure.

Back in the day an inflation range was given to allow for different use and conditions.

 

[Cigar Mike]

I found it interesting that in the manual for my FJR. The tire pressure was 42 psi but there was a note that 36 psi was ok for extended high speed rides. I would have though it was the other way. Lower pressures for dirt is usually better unless you are concerned with pinch flats. But with rim locks and tube tires there is more flexibility. Tubeless tires and sustained high speeds is something else.

 

[showkey]

I wonder if that's a misprint in the FJR manual.......certainly different than the norm.

Here's a link to Avon pressure guidelines:

Avon Motorcycle Tyres North America » Tire Pressure Guidelines

Looks like they are sticking to 2 psi differences but 4-6 psi from solo to fully loaded.

 

[ronsaw]

I found it interesting that in the manual for my FJR. The tire pressure was 42 psi but there was a note that 36 psi was ok for extended high speed rides. I would have though it was the other way. Lower pressures for dirt is usually better unless you are concerned with pinch flats. But with rim locks and tube tires there is more flexibility. Tubeless tires and sustained high speeds is something else.

I'm curious if it has to do with the air pressure increasing slightly as a tire heats up, especially during longer, high-speed riding. An FJR is a pretty good-sized, heavier bike, and capable of sustained high speeds with all of the available power. If my thinking is correct, the tire temps and resulting increase in pressure may be the reason that slightly lowered initial inflation pressures are ok'd by the manufacturer.

 

[maxwellian]

I'm curious if it has to do with the air pressure increasing slightly as a tire heats up, especially during longer, high-speed riding. An FJR is a pretty good-sized, heavier bike, and capable of sustained high speeds with all of the available power. If my thinking is correct, the tire temps and resulting increase in pressure may be the reason that slightly lowered initial inflation pressures are ok'd by the manufacturer.

The lowest safe pressure has mostly to do with heat buildup in the tire. Raising the initial cold pressure can actually reduce the pressure while riding.

I think with lower speeds, at extremely low pressures, steel belt fatigue can be an issue, but mostly if your tires don't get too hot, you're at an okay pressure.

 

[Deleted member 1183]

I have always been of the opinion that 42psi on a solo bike is not right regardless of recommendation. I have found that at such pressures there is not sufficient heat getting into the tyre. At least there was not sufficient getting into the original Z8's. Michelins seem to function a little better but I am still not using 42psi.

One of my bikes that is of similar weight to, or a little lighter than the NC (KTM950SM) has 34 psi recommended front and rear in the handbook. Many of the KTM folks run pressures of between 30 and 35 riding solo. It is recommended to increase slightly for two up, but not to 42psi !

I used to run 36/38 on my NC but have now lowered that to 34/34 similar to my KTM. The bike grips well and there are no issues. However I do believe this bike is sensitive to tyre types. The original Z8's were not good. I changed to Michelins and they were good. I then tried a Bridgestone T30 on the rear and while it is good when heated up, it can be a little slow to get there. I will revert to Michelins from here on. I suppose slight petrol consumption increase and shorter tyre life will result from lower pressures, but that is ok with me as I like to lean a bike, and sideways grip is more important.

 

[Banjoferg]

Griff, have you noticed any specific loss of tire life? I'm already paranoid about tires, for some reason...not sure why. I think it may have been the Z8's that came on my NC. They never gave me any confidence. By the way, I'm heading to your neck of the woods in August and am really looking forward to it.

 

[Deleted member 1183]

Griff, have you noticed any specific loss of tire life? I'm already paranoid about tires, for some reason...not sure why. I think it may have been the Z8's that came on my NC. They never gave me any confidence. By the way, I'm heading to your neck of the woods in August and am really looking forward to it.

Tbh I cannot be sure and am just making an assumption. However I am not noticing any peculiar wear patterns. I am not great at keeping track of mileage as there are a number of bikes in the shed. My main criteria are about grip. Needless to say if there was an exceptionally short life on a tyre I would notice it. The T30 seems to be hanging in there wear-wise.

With regard to Z8's I felt exactly the same as you. I hated them (as did many others on here), because they almost undermined my confidence in the bike. The change to Michelins sorted that. I accept that some folks were ok with them of course.

Is your trip to Ireland on a holiday or business trip ?

 

[DirtFlier]

Street bikes and dirt bikes are completely different in regards to tire pressures. Lower than recommended pressure in street bike tires can lead to a wear condition called "cupping" plus the handling of the bike can be adversely affected. In the dirt it doesn't really matter because the feel of the bike is loose anyhow.

If you want a softer ride, reduce the shock preload and shorten the fork spring spacers.

 

[Banjoferg]

Tbh I cannot be sure and am just making an assumption. However I am not noticing any peculiar wear patterns. I am not great at keeping track of mileage as there are a number of bikes in the shed. My main criteria are about grip. Needless to say if there was an exceptionally short life on a tyre I would notice it. The T30 seems to be hanging in there wear-wise.

With regard to Z8's I felt exactly the same as you. I hated them (as did many others on here), because they almost undermined my confidence in the bike. The change to Michelins sorted that. I accept that some folks were ok with them of course.




Is your trip to Ireland on a holiday or business trip ?

I'm running Bridgestones right now, and so far I like them. I only have about 1000 miles on them. I might try some lower pressures to see how it feels.

My trip is pure holiday. No work allowed.

 

[hojo]

Good read;
Motorcycle Safety & Driveability: motorcycle tire pressures, correct tire pressure, motorcycle owner

 

[Cigar Mike]

The safety aspect of checking the heat of the tires really answers my question. I really like the way the bike rides (less sharp feel on hard hits) and I felt the bike turned much better with the lower pressure. In the turns it seemed like less forced counter steer was required.

 

[serge]

No one seems to mention that higher tire pressure translates into better gas mileage ...

 

[Antarius]

I run maximum allowed pressure, cold, on my street bikes. I ride my street bikes like I'm on the street, not like I'm on a racetrack.

For me, this is usually around 40 in the rear and 38-40 in the front.

My race bike slicks.... run 21lbs front/rear.

 

[Cigar Mike]

I really don't care what others run the pressures at. I asked what is safe. I asked because many people run recommended tires pressures on dual sports and than wonder why their bikes handle so badly in sand and loose soil. I run into people that run the max pressure noted on the tire. I prefer my bikes to handle to my liking. And lower pressures accomplish that in the dirt. Sure the tires may wear a bit faster. But I don't mind that.

Taking from experience off road I was wondering how low of pressures would be unsafe. The lower pressure on the NC improved the ride an handling for me. Since I only ride for fun I don't mind getting a bit less miles from the tires.

 

[hojo]

I guess I can't answer your question to perfection, but I had a friend that let some air out of his tires because he was concerned we might see a BIT of snow on the road as we drove 3 hours to a moto show. When we got there I noticed that his tire was completely worn down and they were pretty much new.

 

[showkey]

I guess I can't answer your question to perfection, but I had a friend that let some air out of his tires because he was concerned we might see a BIT of snow on the road as we drove 3 hours to a moto show. When we got there I noticed that his tire was completely worn down and they were pretty much new.

^^^^^^^^^^^^^^^^^^
That story is more common than you think with a touring bike and high speed. Goes like this....stop for fuel rear tire "looks fine"........ ( what ever that means)........... Next stop the cords are showing.......Tire is found to have 25-30 psi.

That's the good version of the story..........the bad version ends with complete tire failure and a crash !!!!!!!
The story often involves a passenger, open highway and the rear tire.....almost always involves highway speed.


I know or think we were not considering low pressures like 30-32 but extreme care is needed that even 36-37-38 does not unknowingly drop to 30-32.
Seems like 30-32 psi might be enough ?????? ........BUT .......... 30-32 psi...That is 30% lower than the recommended pressure.

Thinking the "safe" pressure is at or very very near the specification ? Tire pressure is often over looked, that's how cars and trucks got mandatory TPMS that alerts at 10% lower than spec. (3 or 4 psi low) gets the light on.

 

[Fuzzy]

From Continental Motorcycle Tire FAQ page.

From years of experience we are aware that motorcyclists sometimes ride on tyres for which the air pressure is not suited to the driving conditions. We do however advise you always to ride at the highest pressure level given from the motorcycle manufacturer. Some amount of comfort will be lost, but that loss will be outweighed by improved safety. In addition the rolling resistance will be lower which will help to save fuel.

Link:
Continental Motorcycle Tyres -Advice on tyre pressure

 

[Jguarfn28]

I'm running 36 front, 44 rear and getting 80mpg.... Riding like I stole her.